Cyanine dyes

ABSTRACT

A CYANINE DYE PREPARED FROM A 2-METHYL BENZOXAZOLE OR 2-METHYL BENZOTHIAZOLE COMPOUND BY REACTION THROUGH THE 2-METHYL GROUP THEREOF. THE PHENYL GROUP OF THE 2METHYL BENZOXAZOLE OR 2-METHYL BENZOTHIAZOLE COMPOUND IS SUBSTITUTED WITH A 2-PHENYL-4-THIAZOLIDONYL-3 RADICAL.

United States Patent Office 3,745,157 Patented July 10, 1973 US. Cl. 260-240.] Claims ABSTRACT OF THE DISCLOSURE A cyanine dye prepared from a 2-methyl benzoxazole or Z-methyl benzothiazole compound by reaction through the 2-methyl group thereof. The phenyl group of the 2- methyl benzoxazole or 2-methyl benzothiazole compound is substituted with a 2-phenyl-4-thiazolidonyl-3 radical.

This is a continuation of application Ser. No. 611,489, filed Nov. 7, 1966.

The present invention relates to a process for preparing new compounds and a process for their use as intermediates for the synthesis of cyanine dyes which are photographic sensitizers.

It is known that in preparing cyanine dyes heterocyclic bases such as the benzoxazole and the benzothiazole can be employed. It is also known that the introduction of certain substitutes in the benzene ring of these bases can make the cyanine dyes derived therefrom especially useful for sensitizing photographic emulsions. One or more of these substitutes may be introduced in the 4,5,6 and 7 positions of the benzene ring.

One object of this invention is to provide new compounds from which cyanine dyes useful as photographic sensitizers can be prepared.

Another object of this invention is to provide cyanine dyes particularly useful as photographic sensitizers.

It has now been found that Z-methyl-benzoxazoles and 2-methyl-benzothiazoles having the general formula -x Y lc...

where X represents an oxygen or sulfur atom and Y repsents the 2-phenyl-4-thiazolidonyl-3 radical wherein the phenyl radical may be substituted (e.g. chloro) or unsubstituted, submit easily to known processes of cyanine dyes synthesis and provide cyanine dyes of particular value as photographic sensitizers. These bases in fact can be salified, in a known way, with alkyl halides, dialkyl sulphates, alkyl p-toluene-sulfonates, aliphatic sultones, aliphatic alfahalogencarboxylic acids, etc. The quaternary salts thus obtained will submit to the usual condensations known in cyanine chemistry, such as the reactions with orthoesters; diarylformamidines; alkylmercaptoand halogenazoles or quinolines; acetanilidovinyl-, acetanilido-methylenbutadienyland hexatrienylderivatives of quaternary heterocyclic salts; acetyl, propionyl-, benzoyl-, triacetyl-, thiopropenyl-, thiobenzoylmethylene benzoor naphto-thiazolines and selenazolines.

(a) Preparation of the 2-methyl-6-[2'-phenyl-4'- thiazolidonyl-3']-benzo-thiazole To 0.01 mole of 6-amino-2-methyl-benzothiazole, in ml. of anhydrous benzene was added 0.01 moles of benzaldehyde, and the mixture was boiled for 20 minutes. 0.02 moles of thioglycolic 'acid disolved in 10 ml. of anhydrous benzene was then added, and the mixture was refluxed for 30 hours. After having removed the solvent, the residue was treated with a sodium carbonate solution and allowed to stand for a few hours. After filtering and washing with water, the product was crystallized from methanol.

Melting point: 161' C. Analysis: calculated N percent, 8.58 Found: N percent, 8.73

(b) Preparation of the 2-methyl-5-methoxy-6-[2-phenyl- 4'-thiazolidonyl-3]-benzo-thiazole It was prepared in a way similar to the preceding compound (a), starting from the Z-methyI-S-methoxy-6-aminobenzothiazole.

Melting point: 175 C. Analysis: calculated N percent, 7.87 Found: N percent, 7.87

(c) Preparation of the Z-methyl-S-[2'-phenyl-4'- thiazolidonyl-3]-benzoxazole It was prepared in a way similar to the compound (a), starting from the 2-methyl-S-amino-benzoxazole.

Melting point: 142 C. Analysis: calculated N percent, 9.04 Found: N percent, 9.11

(d) Preparation of the 2-methyl-5-[2-(2"-chloro)- pheny1-4-thiazolidonyl-3']-benzothiazole It was prepared in a Way similar to the compound (a), starting from the 2-methyl-S-amino-benzothiazole and 2- chlorobenzaldehyde.

Melting point: 179 C. Analysis: calculated N percent, 7.78 Found: N percent, 7.80

(e) Preparation of the 2-methyl-6-[2'-(2"-chloro)-phenyl- 4'-thiazolidonyl-3]-benzothiazole It was prepared in a way similar to the compound (a), starting from the Z-methyl-6-amino-benzothiazole and 2- chlorobenzaldehyde.

Melting point: C. Analysis: calculated N percent, 7.78 Found: N percent, 7.93

The following examples are illustrative of the preparation of cyanine dyes.

EXAMPLE 1 The dye of the structure:

1 o \N/JGHiN/ on Br $11.

Maximum light absorption in ethanol: 4300 A.

3,745,157 3 4 EXAMPLE 2 C.) and of 2-ethyl-mercaptoquinoline iodoethylate were heated to reflux for 30 minutes in pyridine. Pouring the reaction mass into an excess of aqueous potassium iodide precipitated the dye which was filtered, washed with water and with ether, and crystallized from methanol.

The quaternary salt prepared as in Example 1, and 5- acetanilidomethylen B-ethyl-rhodanine, in equimolecular quantities, were dissolved by boiling in ethanol. The resulting solution, to which triethylenamine was added, was 5 heated in a water bath for minutes. The precipitated Maximum absorption in ethanol: from 4380 to 4520 A.

dye was filtered and crystallized from ethanol-dioxane (1:1 ratio). Structure. Melting point: 263 C. 10 0 Maximum absorption in ethanol: 5230 A. L Structurei; Ni N/ CIHI I ,H CH-N s l, t L EXAMPLE 6 1 fl 2 methyl 5-[2'-(2-chloro)-phenyl-4'-thiazolidonyl- H3 S 3']-benzoxazole was salified with a slight excess of di- N ethylsulfate for 40 minutes at 65 C. The resulting quater- I nary salt, washed with ether, was condensed with ethyl EXAMPLE 3 z orthoformate in pyridine by boiling for one hour. Treating the reaction mass with aqueous potassium iodide pre- The quaternary t p pf in Example was cipitated the dye, which was filtered, washed with water refluxed for one hour 1n pyridine with a 100% excess of and with ether, and crystallized fro methanol ethylortho-propionate. At the end of the reaction the reaction mass was poured into a large excess of aqueous po- Maxlmum absorpuon m ethanol 4940 tassium bromide. The dye thus precipitated was filtered, Structure:

CE I H g a: I8 I EXAMPLE 7 The dye having the formula 6 {5 ain, ll; Q 1 5 I C1433 1H5 washed with water and with ether and then crystallized was prepared from 2-methyl-5-methoxy-6-[2-phenyl-4'- from methanol. thiazolidonyl-3']-benzothiazole by salification at C. with diethylsulfate, reaction with ethyl orthopropionate in Maxlmum absorptlonm ethanol: 5630 pyridine, treatment with aqueous potassium iodide and Structure: crystallization from methanol.

-g; a H TQ f-E KD I l O 0 Cl \ci N -CH=7CH N/ \cfia 1 CH; Br 43H:

EXAMPLE 4 The dye having the formula:

5 s CHN JOH=CHCH N-CH 1 (:0 CI I EH A 1 2 t a I i was prepared from the Z-methyl-S-[2'-(2"-ch1oro)-phen- Maximum absorption in ethanol: 5720A. yl-4-thiazolidonyl-3'J-benzothiazole by salification with 5 EXAMPLE 3 diethylsulfate at 65 C., boiling with ethyl ortho-formate The dye having the formula in pyridine, treatment with aqueous potassium iodide and crystallizing from methanol. 5 N CH Maximum absorption in ethanol: 5650 A. i Z l o EXAMPLE 5 N N cfi, l

Equimolecular quantities of 2-methyl-5-[2'-phenyl-4'- W15 1 (3111s thiazolidonyl 3'] benzoxazole diethylsulfate (prepared was Prepared with a Process Similar o t e method defrom the corresponding base and from a slight excess of scribed ill the Italian neutral diethylsulfate by heating for 40 minutes at 65 Maximum absorption in ethanol: 5450 A.

6 EXAMPLE 9 The 2-methyl-6-[-2'-(2"-chloro)-phenyl 4' thiazolis Z donyl-3'1-benzothiazole was sah'fied by heating for 40 L z minutes at 65 C. with neutral diethylsulfate in a N ib fl, excess. The quaternary salt thus obtained was washed 5 A with ether, an equimolecular quantity of the glutaconic aldehyde dianilide hydrochloride was added thereto, and the mixture was refluxed with absolute ethanol in a quantity sufficient to obtain a complete solution. To this solution, 8

cooled to room temperature, was added triethylenamine. 10

The mixture was stirred overnight. The dye precipitated i N CE.

during the reaction was filtered, washed with ethanol and l g i N ether (1:1 ratio) and the product was crystallized from L, anhydrous methanol. 0 0H,

Maximum absorption in ethanol: 7770 A.

CH-N-- s s r t in K JLOH on on CH CH CH CH 3 01 CH2 1? CH2 to obtain cyanine dyes which have their maximum ab- 0- N-CH tical sensitization of photographic emulsions containing A; Q

tificial fibers and plastic materials, as colorants for links, and

By using the procedures of this invention it is possible sorption in almost any portion of the visible light spec- I trum. Although they are particularly suitable for the op- \N/ silver halide and a natural or synthetic colloid, these cyanine dyes are also useful for dyeing natural and aretc. Photographic emulsions containing such sensitizers S N may also incorporate many other compounds serving a g special purposes, e.g. other chemical sensitizers, super- L OCH3 sensitizers, anti-fogging agents, surface active agents, cop- N c ulants, etc. A,

What we claim is:

L A compound selected from the group consisting of and wherein Z is hydrogen or chloro, X is oxygen or sulfur, R is hydrogen or lower alkyl, R and R independently represents lower alkyl groups, and n is 0, 1 or 2.

X (B1 2. A compound of claim 1 of the formula ,J-cn= -on)..=a

\ CH-N s s i Q l U l) and l fi 0% OH N X (B1 C 3 Br Ha A \N CH-\-(J=CH7A cfi, o t a I CH-N 0 3. A compound of claim 1 of the formula s wherein A is a member of the group consisting of 1 =Cs cfi:

30 4. A compound of claim 1 of the formula 5. A compound of claim 1 of the formula 3,745,157 7 8 6. A compound of claim 1 of the formula CHN J-CHl ca I 7. A compound of claim 1 of the formula 8. A compound of claim 1 of the formula CHN s s --N-CH g A) C2 a g 0 on o -oH=( :-oH 00H: \CH2 3 \N/ N/ CH:

CzHa I 2115 10. A compound of claim 1 of the formula References Cited UNITED STATES PATENTS 3,337,573 8/1967 Mariani et a1 260-304 s s N---CH 35 )7 J g E 3 JOHN D. RANDOLPH, Primary Examiner CH: \CQ 1 C;H\I 3 9. A compound of claim 1 of the formula (Lon US. 01. X.R. 2H 40 96-127, 123; 106-22; 260-304 

